define constitutional isomer
constitutional isomers are compounds with the same molecular formula but a different arrangement of internal atoms. they have different physical properties and different names.
How many bonds does H or F,Cl,Br,I tend to form? What is that called?
monovalent - generally forms 1 bond
How many bonds does O tend to form? What is that called?
divalent - generally forms 2 bonds
How many bonds does N tend to form? What is that called?
trivalent - generally forms 3 bonds
How many bonds does C tend to form? What is that called?
tetravalent - generally forms 4 bonds
define covalent bond
two atoms sharing a pair of electrons
define lone pair
a pair of electrons that is not share between two atoms in a molecule. that is, they are only associated with 1 atom.
define octet rule
the octet rule says that second row elements will try to form the necessary number of bonds to fill all 8 "spots" for an electron around each of those atoms (can also go down to 8 in next-to-last shell)
define formal charge. explain how to calculate it.
formal charge is associated with an atom that does not exhibit the appropriate # of valence electrons. a bond contributes 1 electron to an atom. a lone pair contributes 2 electrons to an atom. if the atom does not "have" enough electrons to balance out the nucleus, then it will have a formal charge
electronegativity is a measure of the ability of an atom to attract electrons
in what directions does electronegativity increase?
what is the electronegativity of Hydrogen?
what is the electronegativity of Carbon?
what is the electronegativity of Nitrogen?
what is the electronegativity of Oxygen?
what is the electronegativity of Chlorine?
what are the (roughly) 3 types of intramolecular bonds?
polar covalent bond
describe a covlent bond. what approximate difference in electronegativities results in a covalent bond?
in a covalent bond, electrons are considered to be shared "equally" between the 2 atoms. the difference in electronegativity is 0.5.
describe a polar covlent bond. what approximate difference in electronegativities results in a polar covalent bond?
electrons are not shared equally between the atoms. the difference is electronegativity is between 0.5 and 1.7
describe an ionic bond. what approximate difference in electronegativities results in an ionic bond?
electrons are not shared at all between the atoms. (salt) the difference in electronegativity is greater than 1.7
induction is the movement of electrons towards a more electronegative atom, resulting in a partial charge.
define electron density
electron density is the probability of finding an electron in a particular region of space
describe an orbital (quantum mechanically)
define atomic orbital and list 4 types of atomic orbital
an atomic orbital is an orbital with respect to the nucleus of a single atom. examples include the s, p, d, and f orbitals.
what do simple s and p orbitals look like?
what is a node?
what are degenerate orbitals?
degenerate orbitals are orbitals with the same energy level (for example: 2px , 2py , and 2pz )
what three pinciples/rules govern the way that orbitals are filled?
1. Afbau Principle - the lowest energy orbital is filled first
2. Pauli exclusion principle - each orbital can accommodate a maximum of 2 electrons that have opposite spin
3. Hund's Rule - for degenerate orbitals (like p), one electron is placed in each degenerate orbital first, before the elctrons are paired up
what is the difference between valence bond theory and molecular orbital theory?
valence bond theory is a simple way of describing how atomic orbitals overlap, while molecular orbital theory is a complex way of describing how atomic orbitals overlap.
how are nodes generated (in valence bond theory)?
valence bond theory treats the atomic orbitals as waves. when these waves have equal and opposite magnitude, that creates a node.